MAYBE
0.09/0.18	MAYBE
0.09/0.18	
0.09/0.18	Problem:
0.09/0.18	 gcd(x,0()) -> x
0.09/0.18	 gcd(0(),y) -> y
0.09/0.18	 gcd(s(x),s(y)) -> if(<(x,y),gcd(s(x),-(y,x)),gcd(-(x,y),s(y)))
0.09/0.18	
0.09/0.18	Proof:
0.09/0.18	 Open
0.09/0.18	EOF